The present invention relates to electrical circuit disconnecting means (CDM) for mounting in cabinets and having a forwardly-extending, rotary disconnect that engages a handle on a cabinet door when the cabinet door is closed, and in particular to an improvement in such CDM that provide visual indications of assembly states outside the cabinet as well as provide auxiliary contacts within the cabinet that are controllable irrespective of the position of the door.
Hereinafter, unless indicated otherwise and in order to simplify this explanation, the present invention will be described in the context of a breaker assembly that includes a circuit breaker. Nevertheless, it should be appreciated that the concepts described herein are also applicable to other types of CDM including fusible disconnects, non-fused disconnects, etc.
Referring to FIG. 1, a standard breaker assembly 10 of the prior art includes several components mounted within a cabinet 12 including a door 20 and several components mounted to the door 20. In the illustrated example, the components within the cabinet include a circuit breaker 16, a power contactor 18 and a disconnector or disconnect means 33. Circuit breaker 16 is a three phase breaker including three switches 25, 26 and 58 as well as an auxiliary switch 29.
Contactor 18 includes three power contacts 56, 50 and 42, a relay coil 44 and two control or auxiliary contacts 51 and 54. Contacts 56, 50, 42 and 54 are normally open while contact 51 is normally closed.
Three phase high voltage power is provided to breaker 16, a separate phase provided to each of switches 25, 26 and 58. Similarly single phase low voltage power is provided to switch 29 as well as to each of auxiliary contacts 51 and 54. Each of switches 25, 26 and 58 is linked in series with a separate one of power contacts 56, 50 and 42 while auxiliary switch 29 is linked in series with coil 44. The output of each power contact 56, 50 and 42 feeds a different phase of a three phase load (e.g., a motor). Each of power contacts 56, 50 and 42 as well as auxiliary contacts 51 and 54 is controlled by relay coil 44 such that, when coil 44 is de-energized, the contacts assume their normal condition and, when coil 44 is energized, the contacts transition to their exited states (i.e., normally open contacts close and normally closed contacts open).
In operation, breaker 16 is automatically controlled as a function of system operating parameters to either close switches 25, 26 and 58 thereby providing power to contactor 18 and to close switch 29 thereby exciting coil 44 and in turn transitioning contacts 56, 50, 42, 51 and 534 or to open switches 25, 26, 58 and 29 thereby cutting off power to contactor 18 and de-energizing coil 44.
Referring still to FIG. 1, components in the illustrated example that are mounted to cabinet door 20 include a handle member or handle 24 and “On” and “Off” lights 60 and 22, respectively. On light 60 is linked to auxiliary contact 54 and lights up when contact 54 is closed. Similarly, light 22 is linked to contact 51 and lights up when contact 51 is closed.
Manual disconnector 33 is a mechanical assembly that links to handle 24 and that can be used to manually open the switches in breaker 16. To this end, referring to FIGS. 1 and 2, a shaft 30 extends from breaker 16 toward door 20 and is rotatable about its axis of extension to electrically open and close breaker switches 25, 26, 58 and 29.
Handle 24 is configured to engage the distal end 31 of shaft 30. In particular, a pair of cylindrical locking pins 34 extends horizontally outwardly from either side of the distal end 31 of shaft 30. An extension member 32 extends from the rear side of handle 24 through an opening in door 20, forms a corresponding keyhole 36 that faces into cabinet 12 and includes a first horizontally extending slot 38 sized to receive locking pins 34. Key hole 36 further includes a second vertically extending slot 40 that intersects with slot 38 and is sized to receive the outer end 31 of shaft 30.
During operation, when door 20 is closed, shaft 30 and corresponding locking pins 34 are inserted into keyhole 36 of extension member 32. Handle 24 and member 32 are subsequently rotated counterclockwise along the direction of arrow A, which causes keyhole 36 to correspondingly rotate shaft 30 counterclockwise in the direction of arrow B. Here, rotation in the direction of arrow B closes the breaker switches while rotation in the opposite direction manually opens the switches. As handle 24 is rotated in the direction of arrow A, a door latch (not illustrated) locks door 20 in a closed position. Accordingly, in order to subsequently open door 20, handle 24 is rotated clockwise to unlock door 20 and automatically rotate shaft 30 to open the breaker switches and cut off power to the load. Thus, a user is therefore advantageously unable to access the interior of cabinet 10 without first disconnecting the power contactor 18 from the power source via handle 24.
Here it should be appreciated that the breaker system described above is simplified and is only exemplary and that many other more complex breaker systems exist. For instance, in some cases the breaker 16 may includes many more switches and/or may feed additional contactors or other relay components. As another instance, additional auxiliary contacts may be provided as well as additional lights to indicate other system and component transitional states.
Unfortunately, while the above described assembly facilitates relatively safe breaker operation, the assembly has several shortcomings. First, when assembly components fail, it is relatively difficult to determine the cause of failure using the above described assembly. To this end, referring still to FIGS. 1 and 2, assume that attempts to provide power from the supply lines to the load through cabinet 12 have failed. To identify the cause of failure, with the cabinet door closed, a system operator may attempt transitioning the assembly components and listen for audible tell tale signs of what is going on inside the cabinet. Unfortunately this solution is not very useful as audible noise from the closed cabinet is often difficult to ascribe to the various components mounted therein when the door is closed.
Another solution for determining the source of failure is to open up the cabinet door 20 and visually inspect the components inside the cabinet 12. Consistent with the description above, to open door 20, a system operator turns handle 24 and disconnector 33 to the off position thereby cutting power to contactor 18 and to coil 44. Thereafter, the operator opens door 20 to observe and inspect the components mounted in cabinet 12. While some failures result in easily observable damage to components, in many cases failures do not cause visually recognizable damage. For instance, in some cases normally open power contactor contacts may stick or fuse closed and the fused contacts may not be positioned in any easy to observe orientation or, the source of the sticking may not be readily visually observable. In other cases additional relay contacts may be stuck in abnormal transitional states. In still other cases one or more of the lights (e.g., 60, 22, etc.) used to indicate handle and system states may be burnt out.
Still one other solution for identifying the source of failure is to cause the cabinet mounted components to transition between states while the cabinet door is open. Thus, for instance, referring again to FIG. 1, with door 20 open, a system operator may use a pliers or the like to manually rotate shaft 30 into the On state wherein switches 25, 26, 58 and 29 are closed at which time coil 44 should excite and transition contacts 56, 50, 42, 51 and 54. When contactor 18 transitions between states, a noise can typically be heard (e.g., “ker klunk”) which is recognizable as a state transition. Thereafter the user can transition the breaker again by turning the shaft in the opposite direction to the Off position. While processes that provide power to power contactors and to the power contactor coil while the cabinet door is open are known, clearly these processes are relatively hazardous due to power flow and therefore should be avoided whenever possible.
Second, the assembly described above requires many parts, requires a good deal of time and labor to configure and therefore is relatively expensive. For instance, three separate holes have to be formed in door 20 to mount handle 24 and lights 60 and 22 and then each of those components have to be separately mounted. In many cases the mounting structure for each of the components includes several screws or the like. Exacerbating matters, many breaker assemblies will include several additional lights and control tools such as buttons, knobs, etc, each of the control tools requiring its own door hole or holes to accommodate mounting assemblies. As another instance, after lights are mounted to door 20, wiring has to be run form the lights to the associated auxiliary contacts and power source which increases configuration costs and time considerably.
Third, in most cases breaker assemblies cannot be easily modified to alter assembly functionality. Thus, for instance, where a system operator wants to modify the auxiliary contact logic so that light 60 marked in FIG. 1 as “On” instead illuminates when the handle is in a tripped position, the operator has to rewire light 60 to other system components and, in fact, may also have to add additional components (e.g., another relay) to the assembly.
Fourth, when separate components are provided on door 20 to facilitate control and to indicate assembly states, the front face of the door becomes excessively crowded and cumbersome to use. This is particularly true in cases where the number of status or state lights is appreciable.
Thus, a need exists for a simple, easy to configure, aesthetically pleasing, relatively inexpensive handle assembly that eases the task of diagnosing the health of breaker components.